This invention relates to electronic analogue displays.
The invention is more particularly concerned with displays having an arcuate row of electrically-energisable elements that can be selectively energised to represent a value.
Electronic time switches, clocks and watches may be provided with a digital display in which time is represented by a number, or with an analogue display in which time is represented by selectively energising radial elements arranged around a circular scale.
One problem with such displays arises with the setting or changing of the display. This is especially the case with time switches which have to be programmed with several different times when switching operations are to occur. With time switches, it is often necessary frequently to change the time settings of the switching operations, such as, for example, when controlling domestic heating at weekends.
Several different means are known by which the display can be changed. The display may, for example, have a keyboard in which each key is associated with a different number. By appropriately actuating a combination of keys, a time setting may be entered. Although this may be satisfactory for digital displays where actuation of a key causes display of the number associated with that key, it is less suitable for analogue displays where the time is represented by the position of an element and is therefore less directly associated with the keys on the keyboard. The keyboard also requires a large amount of space.
An alternative arrangement involves the use of only one or two keys. While a key is depressed, the time displayed is advanced in steps, the user releasing the key when the desired time setting is reached. The second key may be used to change the display in the opposite sense. Although such arrangements take up less space, they can be difficult or time consuming to use, since, if accurate setting is to be achieved, the display must be advanced relatively slowly.